Support means of adjustable height, such as tripods, are known in the present art. One such support means is known as a two stage tripod. Such tripods have three leg assemblies, with each leg assembly comprising a first leg unit, a second leg unit and a third leg unit. In order to enable the height of the tripod to be adjusted, the first and second leg units are slidably movable relative to each other and the second and third leg units are also slidably movable relative to each other. Each leg assembly also includes a first fixing means for selectively locking and unlocking the first leg unit relative to the second leg unit and a second fixing means for selectively locking and unlocking the second leg unit relative to the third leg unit. When the first fixing means is in the unlocked position, the first and second leg units are movable with respect to each other, whilst in the locked position the first and second leg units are held in fixed (or locked) in relation to each other. The second fixing means operates in a similar fashion with respect to the second and third leg units. Such tripods are known as two stage tripods because they have two fixing means on each leg assembly.
Such tripods have found wide acceptance and are used throughout the world. Although they are popular, such tripods suffer from the disadvantage of requiring two fixing means on each leg assembly to be operated to properly adjust the height thereof. This can be time consuming. Moreover, the lower fixing means frequently require that the user bend over in order to operate them. This can be inconvenient and cause difficulty if the tripod has heavy camera gear mounted thereon.
One possible solution to the above difficulties has been proposed by Australian Patent No 709257 in the name of Sachtler Agreement (equivalent to U.S. Pat. No. 5,887,835). In this patent, the actuating means for actuating the first fixing means is also connected to the second fixing means such that operating the first actuating means to lock the first fixing means also simultaneously locks the second fixing means. Similarly, operating the first actuating means to unlock the first fixing means also simultaneously unlocks the second fixing means. Thus, locking and unlocking of each leg assembly of the tripod is simplified.